I'm going to start this one with a pic of the foam cutter I used to cut all the 1"x 0.5"x 0.5" bricks I used to build these sections. Quite handy, I say. Picked it up at Hobby Lobby. The blue material you see on it is just poster hanging goo I used to hold my guide in place as I pushed the foam through the cutter.
I began these tiles with cardboard pieces cut into squares, two pieces each glued together perpendicularly so as to help with warping (still got some anyway). I then used my old standby: light-weight spackle to coat one side of the board, then used a straight edge to press out 0.5" 'tiles.' Precision isn't necessary, I want these for gaming. If they get banged up, fine, at least they're seeing use! My first layer of bricks, I used Gorilla Glue, as I wasn't sure how the foam would stick to the spackling compound.
Here's a shot of the first one I did, but hadn't quite got the knack of mass-cutting the bricks. You can see below my masonry skill gets much better. 3 layers of bricks seem right for this section.
A base-coat of black spray paint...
After a medium gray heavy drybrush on the floor tiles, a brown drybrush and the 'dirty' sections, and a dark green wash of the brickwork. Next is a light drybrush of green on the bricks and a very light green wash to the tiles.
The completed 2' x 3' dungeon section!
It looks a little greener in this pic than it actually is. That, or I need to start painting with a brighter lights.
That completes my 1st level of my megadungeon, which I will take a picture of it all together. In the future I may add another 3 tiles to this, but really, due to vision distances in the dark and the modularity of the pieces, they're probably not needed. My next level of the megadungeon will involve different methods of construction and color schemes.